The present invention relates generally to electrical connectors for connecting a power or communication cable to an appliance or telecommunication equipment and more particularly to a rotary electrical connector for a telephone handset.
A rotary electrical connector is used, for example, in conjunction with a cable that connects the handset to the base of a telephone. The purpose of the rotary electrical connector is to prevent the cable from becoming tangled or twisted when used over an extended period of time, which is undesirable.
Rotary connectors generally comprise a spindle at least part of which is contained within a housing. The spindle and the housing are mutually rotatable, in relation to each other, about a common axis. Male and female modular electrical connector's are associated with one or both of the housing and the spindle. The female modular connector associated with the rotary connector receives a male modular connector normally located at one end of the telephone cable, and the male modular connector associated with the rotary connector normally plugs into a female modular connector on the telephone, typically on the handset thereof.
The spindle typically has electrically conductive rings located around its periphery, and these rings are connected by electrically conductive connecting means, extending through the spindle, to electrical contact elements on one of the modular connectors or to other connections with the telephone equipment. The rings are engaged by electrical contact members or wipers typically electrically connected to the other modular connector associated with the rotary connector or to the cord or cable conventionally extending between the handset and the base. There is thus formed a rotatable electrical connection between the telephone cable and the handset.
Examples of rotary electrical connectors of the general type described above are disclosed in Ditzig U.S. Pat. Nos. 4,673,228 issued June 16, 1987 and 4,764,121 issued Aug. 16, 1988. These patents disclose, for the most part, rotary connectors which are separate and discrete from the telephone itself, and are used to retrofit the telephone rather than being part of the original telephone equipment. There are also rotary connector assemblies which are part of the original telephone equipment, these assemblies being "hardwired" to the cable for the telephone handset, for example, and being removably connected internally within the handset and normally inaccessible for removal purposes. Such an assembly is disclosed in Ditzig U.S. Pat. No 4,854,881 issued Aug. 8, 1989. The disclosures of the three aforementioned Ditzig U.S. Patents are incorporated herein by reference.
Rotary connectors of the type disclosed in the first two of the above-identified patents normally project directly from one end of the telephone handset, without any cable connection between the rotary connector and the telephone handset. There is a problem which can arise when an arrangement of that type is utilized. This problem occurs when the telephone handset is inadvertently dropped against a hard surface. The rotary connector projecting from the handset can strike the surface first, absorbing the entire impact of the fall, and if the impact occurs toward the rotary connector end remote from the connection to the handset, the resulting torque can cause the rotary connector to break off from the handset adjacent the end of the rotary connector which engages the handset.
One way of avoiding the problem described in the previous paragraph is to utilize a flexible cable between (a) the male modular connector which engages the rotary connector to the telephone handset and (b) the rotary connector per se. With such an arrangement, the impact is absorbed by the flexible cable between the rotary connector and the male modular connector. Such an arrangement is illustrated in FIG. 13 in the above-identified Ditzig U.S. Pat. No 4,673,228. However, the arrangement disclosed in FIG. 13 of U.S. Pat. No. 4,673,228 has other problems associated with it. More particularly, the wires from the cable generally extend through the interior of the spindle and then are wrapped around the exterior of the spindle to form the spindle rings. It is generally desirable to gold plate the spindle rings to improve the electrical connection between the spindle rings and the contacts or wipers which engage the spindle rings. There are problems associated with trying to gold plate the ends of cable wires which form spindle rings These problems are not associated with spindle rings which are separate and discrete from the cable wires connected to the spindle
The above-identified Ditzig U.S. Pat. No. 4,854,881 discloses an arrangement in which the spindle rings are separate and apart from the cable wires which connect the spindle ring to the telephone handset, but this arrangement requires the utilization of a shorting element or contact jumper to connect the spindle rings to the cable wires.
There is another problem associated with arrangements in which the spindle rings are connected to a male modular connector by an intermediate cable,--namely a possibility that the spindle and the cable will pull away from each other at their connection.